Fat and oil removal installation

ABSTRACT

An installation for the simultaneous separation and removal of fats and oils in waste water, which includes a treatment container chamber for receiving a liquid medium. Out of the treatment container chamber, through a bottom outlet, is an overflow pipe running upwards and which opens outwardly outside of the treatment container chamber as a discharge pipe, so that its inside bottom edge, at the point where it opens outwardly, defines a level of a medium in the treatment container chamber. A support material in the form of a plurality of plastic tubes is wound with lengths of polyester cord colonized with a fat and oil-degrading yeast microorganism Yarrowia lipolytica W1 in the treatment container chamber. A nutrient solution container, with a metering pump for feeding NH 4+  into the treatment container chamber, as required, is included as a source of nitrogen for the fat and oil-degrading microorganism, along with a device for supplying the microorganisms with air. Finally, a metering device having a programmable control device, for metering previously separated fat and oil from either a waste water container chamber arranged outside the treatment container chamber and belonging to the overall installation for removing fat and oil, or from a separate fat-separator, to said treatment container chamber, is included.

BACKGROUND OF THE INVENTION

This invention relates in general to an installation for removing fatsand oils, for which purpose fat and oil-degrading micro-organisms areused in particular. The installation can, in particular, be designed tosimultaneously separate and remove fats and oils in waste water. Thefats and oils in question may be of different types such as e.g.mineral, synthetic or organic. Of particular interest here are the typeof organic fats and oils that occur in waste water from hotels,restaurants and other industrial kitchens above all. The installationcan, however, also be designed for the waste water from food-processingoperations of all kinds such as, for example, slaughterhouses andbutchers shops.

Many local authorities impose discharge regulations on commercial usersof the local sewage system in order to protect their waste waterpurification plants and to prevent drainage pipes from clogging up. InGermany, for example, the maximum volume of organic fats and oils whichsuch commercial operations are permitted to discharge per liter of wastewater fluctuates depending on the local authority between 50 mg and 250mg, with a limit of 50 mg now increasingly being prescribed. This is whysuch businesses install fat-separating plants. In urban areas, onefat-separating plant of this type is usually operated for about every500 residents.

Conventional fat-separating plants, which are designed to separate fatsand oils from water solely by means of gravity, are associated with aseries of problems. Firstly, under the greatly fluctuating operatingconditions that prevail in practice, the actual fat-separating capacityof the installations is often lower than what is required to comply withthe statutory limits. When determining the total content of organic oilsand fats as polar lipophile substances, it is often forgotten that,because of the way fat-separators function, they can only hold backthose parts of the lipophile substances that are separable. They are notcapable of holding back the emulsified, dissolved and dispersed fat thatoccurs because of the detergents that are used and the high temperatureof the waste water from dishwasher systems. This fat occurs in a similarkind of state as the fat in milk, which contains fat particles with adiameter of only 0.1 μm to 10 μm, which do not float to the top.

Furthermore, a conventional fat-separator has to be emptied and cleanedevery two to four weeks, an intervention for which the operator of theinstallation is responsible. Fat-separators in butchers shops have to becleaned at least once a week or, at the latest, when the fat storagecontainer is full. As a general rule, fat-separators in industrialkitchens have to be emptied every two weeks. But the volume and qualityof the waste water fluctuate even amongst industrial kitchens whichprepare the same number of meals. Tests have shown that, because ofdifferences in the types of foods and in the method of preparation, thefat content in the waste water from a hospital kitchen producing 1,000meals per day is approx. 500 mg/l on average, for example, whilst thefat content in the waste water from an army kitchen is approx. 1,500mg/l, i.e. three times more. The fat content per meal can range from 3to 30 g. Depending on the type of kitchen, the fat-separators have to bedrained more or less frequently. Regular draining of the fat-separatorinvolves opening the latter and introducing a suction pipe leading froma waste disposal vehicle. The nauseous smell that occurs as the fat issucked off causes a very unpleasant odour in the immediate vicinity ofthe installation. After the installation has been drained, it is cleanedwith superheated steam. This essential maintenance work causesinconvenience as well as considerable recurrent costs. To reduce thevolumes that have to be transported away, prior art fat-separatingsystems exist in which the separated fat is pressed into separatecontainers so that only the material actually separated off has to betransported away for disposal or recycling. Regular and expensivetransport is still required, however, and this is an additional burdenon the environment.

SUMMARY OF THE INVENTION

Hence it is the task in general of this invention to provide aninstallation for removing fats and oils of whatever origin, which savesall, or part, of the related costs.

In particular, it is a task of this invention to provide an installationfor the separation and subsequent removal of fats and oils in wastewater which renders it unnecessary to regularly transport away thecontent of the fat-separator or the separated fat, thereby saving therelated costs, and, furthermore, which eliminates the nuisance fromsmells generated by a conventional fat-separator.

In one particular embodiment, another task of the installation forseparating and subsequently removing fats and oils in waste water is toachieve improved retention of the fats and oils in the waste water so asto obtain lower limit values of lipophile substances in the dischargedwaste water.

The general task is solved by an installation for removing fats and oilscharacterized by the features of claim 1.

The specific task of providing an installation for the separation andsubsequent removal of fats and oils in waste water is solved by aninstallation with the features of the dependent claim 2.

The additional task of improving the retention of fats and oils in wastewater is solved by an installation with the characterizing features ofthe dependent claim 7.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings show both an installation for the mere removal of fats andoils, as well as a specific installation for separating and subsequentlyremoving fats and oils in waste water. These installations, and the wayin which they function, will be described below in detail with referenceto these exemplary embodiments.

The drawings show:

FIG. 1: a perspective view of a partial section of an installation forremoving fats and oils;

FIG. 2: a perspective view of a partial section of an installation forseparating and subsequently removing fats and oils in waste water;

FIG. 3: a diagrammatic representation of the installation of FIG. 2 seenfrom the side, in a section along the plane A--A in FIG. 2;

FIG. 4: a diagrammatic representation of the installation of FIG. 2,seen from the left, in a section along the plane C--C in FIG. 2;

FIG. 5: a diagrammatic representation of the installation of FIG. 2,seen from the side, in a section along the plane B--B in FIG. 2.

FIG. 6: a perspective view of the installation of FIG. 2, seen from thetop.

DETAILED DESCRIPTION OF THE INVENTION

The installation for removing fats and oils can be designed as anaddition to an existing fat-separating system, in order to continuouslyremove the fat separated in the latter, or as a separate installationfor operating a central disposal unit for waste fats and oils in whichlarge volumes of separated fat from regularly drained fat-separators canbe treated. The heart of the installation is a container chamber with aliquid medium in it, in which there is a microbiological modulecomprising a carrier substance which is colonized with fat andoil-degrading micro-organisms, with a metering device enabling fat andoil to be metered to this container chamber and hence to themicro-organisms in it. The micro-organisms than degrade the fat and oil,thereby lowering the pH-value of the liquid medium in the containerchamber. During this process it is important that the peripheralconditions for ensuring the high activity of the micro-organisms aremaintained. In addition to metering in fat and oil, the micro-organismsare also supplied with air and nutrient solution as necessary.

An installation such as this for removing fats and oils consists, asshown here by way of example in FIG. 1, of a square container 1. Thiscan be made from chromium steel or plastic, with polypropylene beingespecially suitable because it resists fatty acids and is not affectedby low pH-values either. Hence no long-term problems with corrosion arelikely. Inside container 1, separated by partition 3, there is acontainer chamber 9, which contains the microbiological module in theform of a drum 20, and which, when in operation, is filled up to thedrum axle with a liquid medium. The bottom of this container chamber 9forms a channel 11 that slopes downwards and towards the back. At theback of this channel 11, container 9 has an outlet (12). This feeds intoan overflow pipe 55 which runs out of container 1 with its inside bottomedge defining, at the point when it opens out, the level of the mediumin container chamber 9. On side 6 of container 1 there is an electricmotor 22 with angle gear 23, whose drive shaft 21 rotates drum 20 viatwo toothed gears 27,28 disposed one on top of the other. The liquidlevel in container chamber 9 comes up to the axle of the lower gear 28.This ensures that the drum bearings are lubricated and that container 1always remains sealed because drive shaft 21 runs through container wall6 above the level of the liquid. The drum 20 has a drum disc 30,31 atboth ends, and these drum discs are connected around their peripherywith plastic tubes 32 or round plastic bars to form a cage-drum 20. Theinside of this drum can be sub-divided into sections by other plasticrods. When the installation is operated, this drum is filled withcarrier materials for fat and oil-degrading micro-organisms. The carriermaterials, with the micro-organisms colonized on them, are alternatelyrotated with drum 20 through the fat-polluted water and medium, whichcomes up to about the middle of drum shaft 29, and then through the airabove this level. As they do so, they absorb oil and fat, which are thendegraded by the micro-organisms as described below. Built into side wall6 there is a ventilator 36 with a one-way valve which allows air to beblown into the container because the micro-organisms used are aerobic,and need a supply of air. Inside container 1, the exhaust air is blownoutside through a hole in the top of overflow pipe 55 at its highestpoint, or through a special odour filter not shown here. In the exampleshown, the metering device for the fat and oil is designed as follows:attached to container 1 there is an inlet pipe 56 made fromacid-resistant plastic for metering in the oil and fat to be degraded,which runs slopingly into the container and opens out above containerchamber 9.

The plastic pipe 57 running from container wall 6 is of a flexibledesign and is connected to the underside of a plastic pipe 58 with abigger diameter, inside which there is an Archimedes screw 59 which hasa chromium steel shaft and is otherwise also made from acid-resistantplastic. This shaft is driven by a separate motor 60 which can bedisposed as shown here, for example, at the top end of pipe 58. Thebottom end of pipe 58 can now be odourtightly immersed into an existingfat-separating installation, with its bottom aperture being positionedjust below the level of liquid in the fat-separating installation. Pipe58 is held in place with an appropriate retaining device not shown here.Motor 60 can now be switched on as required, whereupon the Archimedesscrew 59 conveys oil and fat up pipe 58 and into container chamber 9 viapipe 57,56, where it is removed by the microbiological module. Theresultant metabolic products are conducted out of container 1 and backinto the fat-separator via pipe 55. If the ambient heat plus the heatsupplied with the fat and oil are not sufficient to ensure an adequatetemperature for the activity of the micro-organisms, a heating devicecan be envisaged in container chamber 9, e.g. in the form of a heatingcoil. Underneath motor 22 there is a box 34 with doors which houses ametering pump. In this box there is also a container for a nutrientwhich is metered to the micro-organisms. For this purpose a hose or apipe 35 runs from this box 34 into the container and on to drumcontainer 9, where the pipe opens out over drum 20. Mounted on the backof the installation (not visible here) there is a switch box whichhouses a programmable electric control device for motors 22,60,ventilator 36 and the metering pump. The installation is sealed shut atthe top with a lid (not shown here) which rests on a rubber gasket. Thisprevents any unpleasant smells from escaping, because when ventilator 36is not in operation, the one-way valve seals container 1, and when it isin operation, no air with smell-carriers can flow from the inside to theoutside against the ventilator current. The lid of the installation canhave hinges, in which case it is advantageously supported by pneumaticsprings with catches at its free end with which it can be locked shut.This type of design means the installation can easily be opened formaintenance and then resealed odourtightly. An installation of this kindcan be designed in line with this principle in a whole range ofdimensions and with other technical solutions, too.

The metering device can, for example, be executed with a pump and theair supply can alternatively be assured by using air screens to blowmicro-bubbles up into container chamber 9 in which the support materialfor the micro-organisms floats. In this case the rotating drum can bedispensed with. Several units can be connected and used in parallel asrequired to achieve the capacity needed to degrade the fat and oil.

The installation for separating and subsequently removing fats and oilsin waste water also operates as a fat-separator itself in that gravitycauses the separable fats and oils carried in with the waste water tofloat to the top of the water where they form a layer of fat and oil onthe surface. The separated fat and oil is then metered to amicrobiological module in the same way, where the fats and oils aredegraded microbiologically. The installation can also be fitted withdevices designed to accumulate particles which are difficult to separateto make them float to the top; furthermore, the waste water treated thusfar can be forced to flow through special material with a particularaffinity with fat and oil particles so as to absorb them.

The installation shown in FIG. 2 for the separation and subsequentremoval of the separated fat will now be described. It consists of asquare container 1. This can be made from chromium steel or plastic,with polypropylene being especially suitable because it resists fattyacids and is not affected by low pH-values either. Hence no long-termproblems with corrosion are likely. The installation illustrated issized for a kitchen with a capacity of about 400 meals per day. It is1.30 m long, 0.70 m wide, 1.50 m high and holds about 900 liters ofwaste water. This size of installation is by far the one most oftenrequired and for a kitchen of this capacity, the installation is socompact that it can easily be transported down relatively narrow flightsof stairs, as are often encountered in old buildings, and built into acellar. The installation can of course be made correspondingly biggerfor other kitchen capacities. The volume which the installation willneed to be able to hold is determined using empirical values forconventional fat-separators and must ensure that, even if there is asudden large surge of water, the average time the waste water remains inthe installation is sufficiently long enough to allow the separable fatsand oils to float to the top. Leading into container 1 there is an inletpipe 2, through which the fat-polluted waste water flows intocontainer 1. Inside the container there is a first partition 3 whose topedge 4 is fitted with a kind of comb 5. The whole of container chamber 7in container 1 between side wall 6 and partition 3 is filled with wastewater when the installation is operated. In this section 7, theseparable fats and oils float to the top and form a layer on the surfaceof the water. When the installation is operated, this layer of oil andfat flows over edge 4 and through comb 5 so that primarily fats and oilsarrive in the space on the other side of partition 3. Comb 5 holds backany floating solids. Waste water naturally flows over the top ofpartition 3 with the fats and oils. The volume flowing over thepartition at any one moment coincides with the volume flowing in at thesame moment through inlet pipe 2. In the container chamber 8 behindpartition 3, any separable fats and oils still suspended in the wastewater undergo further separation. In this container chamber 8, installedfrom above and sealed off from container chamber 8, there is a separatecontainer chamber 9 with a partition 10 which contains a microbiologicalmodule in the form of a drum 20. The bottom of this container chamber 9forms a channel 11 which slopes downwards towards the rear. At the rearof this channel 11, container 9 has an outlet 12. This runs into anoverflow pipe 13, and, via this, back into container 8, with theaperture 14 of overflow pipe 13 being disposed a few centimeters abovethe level of the bottom edge of discharge pipe 15 of container 1.Underneath channel 11, container chamber 8 has a rearwardly slopingfloor 16 with openings in the rear corners, or with a gap along itswhole width between it and the side wall 17 of container 1. The space 18underneath the sloping floor 16 is free here, and out of it dischargepipe 15 runs through partition 3 into container chamber 7, inside whichit runs upwards and then to the outside at a level slightly below thelevel of inlet pipe 2. Container chamber 7 functions as a sludge trapand settling zone for any solids carried into the installation with thewaste water. The sludge and solids that collect can be drained away fromtime to time via drainage pipes 19. If there is no slope available forthe drainage operation, a pump is connected to drainage pipe 19. Throughthe length of container chambers 7 and 8 up to partition 10 of container9 extends a drive shaft 21 which is made from stainless steel. It isdriven by an electric motor 22 with angle gear 23. In the vicinity ofcontainer chamber 7, a paddle 24 is attached to this shaft 21. One orseveral such paddles, which rotate with shaft 21, continuously agitatethe top layer of fat, oil and water in container chamber 7. Tests haveshown that this is a very effective way of making fats and oils float tothe top on the one hand, and solids and sludge sink to the bottom on theother hand. In the middle, an intermediate bearing 25 for shaft 21 ismounted on partition 3. In the vicinity of container chamber 8, that isto say, between partition 3 and partition 10 of container 9, a scooppipe 26 is mounted on drive shaft 21, whose purpose will be explainedbelow. At the end of shaft 21, a plastic toothed gear 27 is mounted onpartition 10 on a reinforcing plate 40. This gear meshes with anothergear 28 of the same size disposed underneath. This gear 28 is connectedwith a shaft 29 made of plastic, which forms the axle of a drum 20housed in container chamber 9. This drum 20 has a drum disc 30,31 atboth ends, and these drum discs are connected around their peripherywith plastic tubes 32 or round plastic bars to form a cage-drum 20. Theinside of this drum can be sub-divided into sections by other plasticrods. When the installation is operated, the drum is filled with carriermaterials for micro-organisms, as will be described below, and drum 20then alternately rotates these carrier materials with the colonizedmicro-organisms through the fat-polluted water which comes up to aboutthe middle of drum shaft 29, and then through the air above this level.The power level of the motor for rotating the drum for this size offat-separator for a kitchen with a capacity of 400 meals per day is 370watts. Hence approx. 9 kWh of electric energy are required per day(24-hour operation). Built into side wall 6 there is a ventilator 36with a one-way valve which allows air to be blown into the containerbecause the micro-organisms used are aerobic and need a supply of air.The exhaust air is blown into the sewage system through a hole 33 in thetop of discharge pipe 15 at its highest point, or outside through aspecial odour filter not shown here. If the ambient heat plus the heatsupplied with the fat and oil are not sufficient to ensure an adequatetemperature for the activity of the micro-organisms, a heating devicecan be envisaged for containers 7,8 and 9 in particular, e.g. in theform of a heating coil.

Underneath motor 22 there is a box 34 with doors which houses a meteringpump. In this box there is also a container for a nutrient which ismetered to the micro-organisms. For this purpose a hose or a pipe 35runs from this box into the container and then on to drum container 9,where the pipe 35 opens out over drum 20. Mounted on the back of theinstallation (not visible here) there is a switch box which houses aprogrammable electric control device for the motor 22, the ventilator 36and the metering pump. The way in which the control device works will beexplained below. The installation is sealed shut at the top with a lid(not shown here) which rests on a rubber gasket. This prevents anyunpleasant smells from escaping, because when ventilator 36 is not inoperation, the one-way valve seals the container, and when it is inoperation, no air with smell-carriers can flow from the inside to theoutside against the ventilator current. The lid of the installation canhave hinges, in which case it is advantageously supported by pneumaticsprings with catches at the free end with which it can be sealed shut.This type of design means the installation can easily be opened formaintenance and then resealed odourtightly.

FIG. 3 shows a section through the installation of FIG. 2, seenlengthwise on. The individual parts are represented diagrammatically andthe Figure shows a section through the installation along the plane A--Ain FIG. 2. The installation has a lid 46 which rests on a rubber gasket.An odour filter 47 is built into this lid. In the top left-hand cornerof the Figure ventilator 36 is indicated, built into container wall 6.The ventilator blows air from below via a pipe (not shown here) into acage, for example, in which there is a piece of Styropor cut to fitinside the cage. When the ventilator is operated, the Styropor piece islifted and air can pass through the cage into the container. When theventilator is not operated, the Styropor piece lies on top of theventilator pipe aperture and seals it. The inlet pipe 2 is shown underventilator 36. The fat and oil-polluted waste water flows through theinlet pipe 2 into the first container chamber 7, with a splashback wall61 being disposed in front of the aperture of the inlet pipe. If thereis a surge of inflowing waste water this wall prevents a wave fromforming on the surface of the liquid in container chamber 7, which wouldcause an excessive volume of water to flow over edge 4 of partition 3into the next container chamber 8. But the main purpose of thesplashback wall 61 is to ensure that the solids and sludge in the newlyinflowing water sink to the bottom of container chamber 7 so that onlythe top layer, consisting essentially of fat and oil and some water,flows over edge 4 into the next container chamber 8. In the vicinity ofcontainer chamber 7, drive shaft 21 carries two paddles 24 whichcontinuously agitate the top layer of the liquid. The level of theliquid in container chamber 7 is indicated by a triangle 38 and isdefined by the top edge 4 of partition 3. The fat and oil which haspreviously floated to the top flows over this edge 4 together with waterinto the next container chamber 8. Triangle 39 indicates the slightlylower level of liquid in this container chamber 8. In the vicinity ofcontainer chamber 8, drive shaft 21 carries scoop pipe 26, which iseccentrically attached to drive shaft 21. An inlet channel 37 runsthrough the top of partition 10 of drum container 9. When scoop pipe 26rotates with shaft 21, it collects a portion of fat, oil and water inits inlet aperture, which is shown pointing towards the rear of theinstallation. When the scoop pipe 26 rotates out of the position showntowards the rear and then upwards, the liquid collected in pipe 26 flowstowards its outlet aperture and is then, when scoop pipe 26 projectsupwards on shaft 21, poured onto inlet channel 37, via which it flowsinto drum container 9. Drive shaft 21 drives drum 20 via gear 27 andgear 28 underneath, and keeps it rotating continuously. Here, incontrast to FIG. 2, gears 27,28 are disposed by way of a variant insidedrum container chamber 9, instead of in front of partition 10. The drumshaft 29 is mounted on both sides on plastic bearings 53,54. Gear 27 canbe displaced a little way towards these bearings along drive shaft 21 sothat drum 20 can then easily be lifted out of bearings 53,54 and removedfrom drum container 9. The level of liquid in drum container 9 isindicated by triangle 41. It can be seen that the liquid comes up toabout half way up shaft 29 carrying drum 20. This ensures that bearings53,54 of drum shaft 29 are lubricated by the liquid. Drum container 9has a floor which forms a sloping channel 11. From outlet 12 in channel11, an overflow pipe 13 runs back under drum container 9 and thenupwards to the axle height of drum shaft 29. This aperture 14 ofoverflow pipe 13 defines the liquid level 41 in drum container 9.Underneath drum container 9, a sloping floor 16 is built into container1 with openings 43 in the form of holes or slots. Underneath floor 16 inthis Figure, there are slats 44 which run upwards at an angle, whichhave a surface with an affinity for fat and oil. A plurality of slatsare disposed adjacent to each other and extend across the entire insidewidth of container 1. From the zone occupied by these slats 44, whichforms container chamber 18, a discharge pipe 15 runs through partition 3and then upwards, where it runs to the outside through container wall 6.The bottom edge of discharge pipe 15, at the point where it runs throughcontainer wall 6, defines the liquid level 39 in container chamber 8. Inthe bottom left-hand corner of container 1, there is a drainage pipe 19with a tap for the sludge and solids that collect in container chamber7.

FIG. 4 shows a diagrammatic representation of the installation in asection along the plane C--C in FIG. 2. This diagram helps to illustratehow scoop pipe 26 functions. Scoop pipe 26 is mounted eccentrically ondrive shaft 21. The inlet aperture 45 of scoop pipe 26 describes thecircle indicated. The circle shown slightly below indicates theperiphery of drum 20. The outlet aperture 48 of scoop pipe 26 isdirected towards the back of the installation in the direction of driveaxle 21. Underneath outlet aperture 48 of scoop pipe 26 can be seeninlet channel 37, which runs through opening 49 into drum container 9.Drive axle 21 can rotate in both directions. If it rotates clockwise inthe Figure shown, then scoop pipe 26 with its inlet aperture 45 isimmersed in the separated, floating oil and fat in container chamber 8and collects a portion thereof, with this portion also possiblycontaining some water. Triangle 39 indicates the level of liquid incontainer chamber 8. If scoop pipe 26 now continues to rotate clockwise,the collected portion in pipe 26 flows towards its outlet aperture 48 toend up being poured out onto inlet channel 37, via which the fat, oiland water flow through opening 49 into drum container 9. Drive shaft 21drives drum 20 simultaneously, and keeps it rotating. Because the drumis driven by the two toothed gears (not shown here), it rotates in theopposite direction to drive shaft 21. If, however, drive shaft 21 nowrotates anti-clockwise in the illustration shown, scoop pipe 26 collectsnothing and drum 20 rotates clockwise. By switching the direction ofrotation from time to time, portions of fat and oil can very easily beconveyed into container chamber 9 with constantly rotating drum 20. Tothe right of the Figure one can see the overflow pipe 13, whose aperture14 defines the level 41 in drum container 9. Underneath drum 20, therearwardly and downwardly sloping channel 11 is drawn in, which formsthe floor of drum container 9. At the lowest point there is an outlet12, which runs into overflow pipe 13. The installation has a lid 46,which rests on a rubber gasket, into which an odour filter 47 is built.

FIG. 5 is a partial section along the plane B--B in FIG. 2. The Figureshows the level 38 in container chamber 7, which is slightly higher thanlevel 39 in adjoining container chamber 8, from which fat and oil iscollected. Inserted in the vertical section of discharge pipe 15 thereis a snugly fitting pipe 50 with bottom 51 which is porous at the topand bottom, it being perforated as illustrated, for example. At the topof pipe 50 there is a handle 52. Its inside is filled with specialmaterial 42 with the capacity to accumulate, that is to say, absorb,fat. A suitable filler material is, for example, the product MELT-BLOWN,a textile composite material made from polypropylene in granular form oras a tape, manufactured by ECOTEXTIL, 277 Hornatky un Neratovic, CzechRepublic. One gram of this material can accumulate approx. 12 to 18grams of fat. As liquid flows through pipe 50, any not yet separated orinseparable fat and oil particles are largely captured and retained bythis material. When the material capacity is exhausted, pipe 50 can beremoved by pulling on handle 52. The material is then removed andreplaced. The oil and fat-bearing material is recycled, i.e. it ispressed out or centrifuged. Solvents for extracting fats and oils canalso be used. The fat and oil from the recycling process can be returnedto container chamber 8 of the installation.

FIG. 6 shows the installation seen from the top. All the partsdesignated by numerals have already been described in connection withthe other Figures. In contrast with FIG. 2, the discharge pipe 15 isshown here as a square discharge channel.

The installation of FIGS. 2 to 6 not only separates fats, it alsoremoves the separated fat and oil by means of the microbiological modulewhich will now be described and explained in more detail. The moduleconsists of the drum container 9, which is functionally separate fromthe actual fat-separator, and the drum 20, which rotates in thiscontainer. This drum 20 is filled with carrier material for special fatand oil-degrading micro-organisms. These aerobic micro-organismscolonize the carrier material and as the drum 20 rotates, they arerepeatedly immersed in the liquid in which the drum 20 rotates, wherethey pick up oil and fat and then emerge from the liquid and aretransported through the air, which supplies them with oxygen. Throughoutthis process they degrade the fats and oils. With regard to thetechnology of the installation it is very important that thisdegradation process proceeds under conditions that are alwaysapproximately the same, i.e. within a certain range in respect of thetemperature and the pH-value of the liquid medium in drum container 9.With this in mind, it is important that the volume of fat and oilmetered in per unit of time is kept within a certain range, or, ideally,is kept constant. That is the essential factor for ensuring successfulmicrobiological degradation in an installation of this type. Theseperipheral conditions can be guaranteed by ensuring that themicro-organisms in said drum are allowed to act in a container which isseparate from the actual fat-separator, in which the required conditionscan be maintained continuously over time. This microbiological moduleessentially only receives the fat and oil to be degraded, even though alittle water may also happen to be carried in as well. The waterresulting from the degradation process has a low pH-value and isconveyed through overflow pipe 13 into container chamber 8 of thefat-separator, where it mixes with the large volume of water in there sothat its low pH-value has practically no effect on the pH-value incontainer chamber 8 after it is mixed in. Separating drum container 9from the other parts of the installation also forms a buffer againsttemperature fluctuations. If a surge of hot water flows into theinstallation from a dishwasher, this has virtually no impact on thetemperature in drum container 9. Neither is the quantity of fat and oilthat is fed in affected. The electric control device is used to ensurethat drum 20 rotates continuously, thereby ensuring that paddles 24 andscoop pipe 26 also turn continuously. Most of the time, however, scooppipe 26 does not collect anything. By means of a timer switch theelectric control device is set or programmed to stop the motor everyhour, for example, and then rotate it a few times in the oppositedirection. During this process scoop pipe 26 scoops a few portions intodrum container 9. How often the direction of rotation is reversed andhow many times the scoop pipe 26 is made to scoop each time this happensis adapted from case to case in line with the operating conditions ofeach kitchen, and programmed with the electric control device. It isexactly the same for ventilator 36. The ventilator need not runcontinuously, but can instead occasionally be switched on for a certainperiod by a control program depending on the required activity of themicro-organisms. The same also applies to the metering pump forsupplying additional nutrient solution for the micro-organisms in drum20.

The specific microbiological aspects of this fat and oil degradationwill be disclosed below: there are a considerable number ofmicro-organisms which produce enzymes that hydrolyse the ester bonds oftriacylglycerols, i.e. oils and fats. These enzymes are referred to aslipases (triacylglycerol of acylhydrolase, EC 3.1.1.3). In the food andchemical industries, lipases are commonly used in a pure form(decapsulated or immobilized) to hydrolyse triacylglycerols. Thosemicro-organisms which are the most important lipase producers includelipolytic yeasts, which are often exploited in biotechnologicalcontexts. Their lipolytic enzymes are species-specific. They can beinduced by various triacylglycerols or oleic acid. With lipolyticyeasts, the lipase synthesis can often be positively influenced by thesource of oxygen selected and by the presence of citrate. Citric acidand, in some cases, isocitric acid as well, are the main metabolicproducts resulting from the exploitation of hydrocarbons, oils and fatsas a nutrient for these micro-organisms. The accumulation of thesemetabolic products in the culture medium causes rapid acidification. Aparticularly suitable micro-organism for this installation for removingorganic oils and fats is the lipolytic yeast Yarrowia lipolytica, withthe strain Yarrowia lipolytica W1 being particularly suitable. Themorphological and physiological properties of this yeast strain Yarrowialipolytica W1 will be described and explained below. The yeast strainYarrowia lipolytica W1 does not ferment maltose, saccharose, lactose,glucose, galactose or raffinose. It does not assimilate any nitrates,but it does assimilate L-lysine and erythritol. It grows at atemperature between 5° C. and 35° C. In a liquid culture medium witholeic acid as the only source of carbon, it forms elliptical to ovalcells. After 120 to 142 hours of cultivation, it forms pseudomyceliumand real mycelium. No pigmentation occurs. It requires neither thepresence of vitamins, nor any kind of growth stimulators to grow in asynthetic medium. This strain is sensitive to nystatin. It is not verysensitive, however, to changes in the pH of the medium, or to changes inthe ionic force of the medium. If exposed to extreme temperatures for ashort period, or if there is a temporary oxygen deficit in the medium,it survives very well. It has a very good capacity for adhering to thesurface of the fat particles. It produces the emulsification substancethat enlarges the surface of the degraded oils and fats for colonizationwith yeast. It is very good at colonizing synthetic carriers withsuitably electrically charged surfaces and a jointed or non-jointedsurface structure. This yeast Yarrowia lipolytica, in particular thestrain known as Yarrowia lipolytica W1 (Harrison) van der Walt et. vonArx is the amorphous form of Candida lipolytica (Harrison), Diddens et.Lodder. This micro-organism was isolated from soil contaminated withpetroleum near a source of petroleum in Hodonin in the Czech Republic,and deposited on Apr. 16, 1996 at the Czech Collection ofMicro-organisms under number CCM 4510, and a Viability Statement wasissued under the same number. The address of this internationallyrecognized depositary under the Budapest Agreement is: CCM--CzechCollection of Microorganisms, Masaryk University, Tvrdeho 14, CR-602 00Brno. A copy of the Receipt in the case of an Original Deposit and acopy of the Viability Statement are enclosed as Appendix 1 and Appendix2 of the description.

The high resistance of Yarrowia lipolytica W1 to the action of externalfactors, the low requirement for nutrients in the surroundingenvironment, its excellent viability and high lipolytic activity make itpossible to exploit this micro-organism for the biodegradation of fatsand oils in closed containers and for the continuous biodegradation ofoils, fats and oil emulsions in the process of cleaning waste watercontaminated in this way. The yeast strain is first propagated andinduced in a synthetic or organic medium in the presence of fatty acidsor oils. Synthetic carriers for the micro-organisms are then colonizedwith the yeast, or the micro-organisms are used directly in thecontaminated waste water. The degradation of the oils and fats proceedswith a supply of air and a sufficient concentration of nitrogen, withthe ratio between the carbon contained in the oil or fat in this medium,and the nitrogen, should be kept within the limits of 60 to 100:1. Theoptimum conditions for carrying out the process for biodegrading oilsand fats using this yeast are with a pH-value of the medium between 2.0and 5.0 at a temperature of 20° C. to 35° C. For the purpose ofpreparing and inducing Yarrowia lipolytica W1 it is best to use theorganic or synthetic culture medium, which forms a source of nitrogenand phosphorus, in a soluble form, to which are added other inorganicsalts and trace elements plus oleic acid or vegetable oil. The initialpH-value of the culture medium can advantageously be adjusted withcitric acid to between 3.5 and 4.5. With an intensive through-flow ofair, i.e. 0.3 to 1.0 liter of air per 1 liter of medium per hour at atemperature of 25° C. to 30° C., the cultivation time is between 24 and72 hours.

The end products of the biodegradation of the oils and fats are carbondioxide (CO₂), biomass and citric acid as the major metabolite. Otherorganic acids such as acetic acid, malic acid, fumaric acid andoxoglutaric acid may also occur. During the continuous biodegradation ofthe fat by the cells, however, these metabolites may also be convertedinto citric acid or used to form biomass. The primary advantage of thisprocess for the biodegradation of fats and oils is that the resultantmetabolites are not toxic and can easily be broken down by the usualmicroflora in biological waste water purification plants. Because themicro-organism used was isolated from the natural environment and hasnot been genetically modified, and because it belongs to the species ofnon-pathogenic yeasts widely used in the food industry, too, (productionof the citric acid, preparation of nutrient proteases and lipases etc.),there is no danger of any negative impact on the environment or on humanhealth.

Tapes or fluffy cord made from synthetic fibre, preferably polyester,which can be colonized with the cells induced by Yarrowia lipolyptica W1are suitable as carrier material. These tapes or cords are wound insections of about 1.50 m on small plastic tubes made from syntheticpolymers, which are about 10 cm long with a diameter of 3 cm to 4 cm,for example. The tubes are made from polyvinylchloride, polyethylene orpolypropylene, for example. The drum 20 of the installation, which canbe sub-divided into several sections, is filled with tubes wound likethis. This carrier material is then colonized with the cells induced byYarrowia lipolyptica W1, whereupon the installation is ready to operateand the fat and oil can be fed in continuously or periodically. Duringpractical tests with the installation, the medium in drum container 9received NH₄ ⁺ as a source of nitrogen at a concentration of 100 mg/l to400 mg/l. The pH-value in the medium settled to between 1.02 and 3.0within 35 weeks. The temperature of the medium fluctuated between 25° C.and 28° C. The water discharged from the installation contained oil in aconcentration of 38.25 mg/l to 48.12 mg/l (gravimetric analysis afterextraction into organic solvent).

Representatives of the species Yarrowia lipolytica, in particular thestrain Yarrowia lipolytica W1, demonstrate good lipolytic activity inthe presence of oils and fats, similar to when emulsions of thesesubstances are present in the water medium. The biodegradation rate ofthese pollutants of the water medium by the cells of the strain Yarrowialipolyptica W1 is relatively high when the pH-value is somewhere betweenthe broad range of 0.8 and 7.0, and at temperatures from 5° C. to 35° C.The prerequisites for achieving optimum physiological activity ofYarrowia lipolyptica W1 are: firstly, an adequate supply of oxygen, i.e.between 0.3 and 1.0 liter of air per 1 liter of waste water per hour;secondly, an adequate concentration of NH₄ ⁺, i.e. at least 60 mg/l,and, thirdly, a concentration of 0.1% to 3% (w/v) of fat or oil in themedium. The waste water discharged from the installation is only veryslightly acidified by the citric acid. Treating it in community wastewater purification plants poses no problem whatsoever.

We claim:
 1. An installation for removing fat and oil, comprising:atreatment container chamber for receiving a liquid medium, dischargingout of said treatment container chamber via a bottom outlet, and havingan overflow pipe which runs upwards and opens outwardly outside of saidtreatment container chamber as a discharge pipe, so that its insidebottom edge, at the point where it opens outwardly, defines a level of amedium in said treatment container chamber; a support carrier materialin the form of a plurality of plastic tubes wound with lengths ofpolyester cord colonized with a fat and oil-degrading yeastmicroorganism Yarrowia lipolytica W1 in said treatment containerchamber, said microorganism Yarrowia lipolytica W1 being deposited withinternational depository CCM 4510 of Apr. 16, 1996 at the CCM CzechCollection of Microorganisms, according to the Budapest Treaty; anutrient solution container with a metering pump for feeding NH₄₊ intosaid treatment container chamber, as required, as a source of nitrogenfor said fat and oil-degrading microorganism; means for supplying saidmicroorganism with air; and, a metering device having a programmablecontrol device, for metering previously separated fat and oil fromeither a waste water container chamber arranged outside said treatmentcontainer chamber, or from a fat-separator, to said treatment containerchamber.
 2. The installation for removing fat and oil according to claim1, further comprising an outer container with an inlet pipe and adischarge pipe for the separation and subsequent removal of fats andoils from the waste water, said outer container having at least onewaste water container chamber for separating fats and oils frominflowing waste water, and a separate treatment container chambercontaining a carrier material colonized with said fat and oil-degradingmicroorganism.
 3. The installation for removing fat and oil according toclaim 2, wherein said treatment container chamber contains therein arotatably mounted drum housing, said carrier material colonized withsaid fat and oil-degrading microorganism, said drum being driven byelectrical means, and wherein said metering device comprises a scooppipe rotatable around an axle, so that with each revolution of saidscoop pipe, a definite portion of oil, fat and water is pourable onto aninlet channel leading into the treatment container chamber.
 4. Theinstallation for removing fat and oil according to claim 2, whereinfollowing immediately from said inlet pipe, for separating oils andfats, said outer container has, at least, one settle container chamberin which sludge and solids are able to settle, followed by an additionalseparation container chamber, separated by a first partition wall, andbeing at a lower level for the separation of fat and oil from the wastewater, from said settle container chamber, separated oil and fat beingconveyable with said metering device into said treatment containerchamber, which is separated from said separation container chamber by asecond partition wall and a channelled bottom, and in which saidtreatment container chamber there is carrier material colonized with fatand oil-degrading microorganisms, and from the bottom of said treatmentcontainer chamber an overflow pipe opens outwardly in said separationcontainer chamber above a predetermined level in said separationcontainer chamber.
 5. The installation for removing fat and oilaccording to claim 4, wherein underneath said separation containerchamber, and separated from the latter by a sloping, pervious floor,there is a series of slats in a separate container flowing chamberdisposed closely together and slopingly with oil-attracting surfaces,through which waste water is forced to flow before it enters saiddischarge pipe, and in that said discharge pipe runs through a flowcontainer, the inside of which is filled with a material with thecapacity to absorb fat, after which said discharge pipe runs out of saidouter container.
 6. The installation for removing fat and oil accordingto claim 5, wherein said flow container is a pipe with a sealed bottomwhich is pervious at both ends and introduced through an opening so thatit fits snugly in a rising section of said discharge pipe.
 7. Theinstallation for removing oil and fat according to claim 1, furthercomprising at least one of: (1) a ventilator having a one-way valve,with which air is able to be blown into said treatment containerchamber, or (2) an oxygen or air-supplying device with which finemicro-bubbles of air or oxygen are able to be pumped into said treatmentcontainer chamber; and in that for the purpose of removing exhaust air,said treatment container includes an odor filter or the installation hasan opening in its discharge pipe; and wherein the metering devicecomprises a nutrient solution container with a metering pump for feedingnutrient solution into said treatment container chamber as required forsaid fat and oil-degrading micro-organism; and wherein the installationalso comprises a programmable electric control device which regulatesquantities of fat and oil, air or oxygen and NH4+ metered into saidtreatment container chamber.
 8. The installation for removing oil andfat according to claim 1, wherein said metering device comprises a pipewith an Archimedes screw drivable by a motor, and in that from themetering device pipe, a further pipe branches off into said treatmentcontainer chamber and opens outwardly there, and in that an overflowpipe runs out of said treatment container chamber and defines a level insaid treatment container chamber at its highest point.
 9. Theinstallation for removing oil and fat according to claim 1, furthercomprising a lid atop said installation for sealing gases and odorswithin said installation, said lid resting on a rubber gasket with saidlid being pivotable on hinges and supported by means of pneumaticsprings.